0db, -3db, or -6db for tuning

What are most songs recorded at?

I know a lot of people say to tune your subwoofer amp with a test tone of 0db, just in case you hit a song that is 0db. However I feel like most songs are recorded much lower, which in turn loses you tons of power after you tuned your system and you waste your time putting big money into getting a big amp, if you tuned it at 0db.